1. Field of the Description
The present invention relates, in general, to projecting or displaying video/animated or still three dimensional (3D) images, and, more particularly, to autostereoscopy and autostereoscopic projection systems such as those adapted to display ghost or latent 3D images without requiring accurate tracking of a viewer's right and left eye or glasses, headgear, or other equipment that has to be worn or used by a viewer.
2. Relevant Background
There are numerous entertainment and other settings where it is desirable to create a unique visual display. For example, theme or amusement parks may include rides or walk-through attractions where guests (or “viewers”) are entertained by a unique visual effect or illusion. Pepper's ghost is an illusionary technique used by magicians, by ride or attraction designers, and others to produce a 3D illusion of a latent or ghost-like image. Using a simple piece of plate glass and special lighting techniques, Pepper's ghost systems can make objects appear and disappear within a scene or room.
Generally, these systems include a main room or scene that is readily viewed by a guest or viewer and a hidden room that is not visible to the viewer, and both rooms may be identical in their physical structure including furniture and other objects except the hidden room may include additional objects or characters such as a ghost. A large piece of glass or a half-silvered mirror is situated between the viewer and the scene at an angle, such as at about 45 degrees. When the main room is lit and the hidden room is darkened, the viewer only sees the main room as the hidden room does not reflect from the glass and the sheet of glass is itself hard to see as it typically extends across the entire view of the main room.
Pepper's ghost then becomes very visible to the viewer when the entire hidden room or portions such as the ghost or other character are brightly lit. Since only a portion of the light cast upon the ghost or other objects in the hidden room is reflected from the glass, the reflected images appear as latent or ghostly images relative to the objects in the main room (e.g., the reflected images or images superimposed in the visible room may appear to float). The Pepper's ghost image is a 3D image that may be a still image or animation may be provided such as with animatronics providing the “ghost” or by placing a live actor in the hidden room. In many current systems, a 2D display is used as it is more dynamic and controllable and does not require a live actor or expensive animatronics. However, this results in a 2D image or flat object being positioned within a 3D set (e.g., the main room). In a broad sense, the Pepper's ghost systems may be thought of as implementing autostereoscopy, which is generally a method of displaying 3D images that can be viewed without the use of headgear or glasses on the part of the user.
FIGS. 1A and 1B illustrate a traditional layout for a Pepper's ghost display 100 for use in creating a 3D display 150 for a viewer 105. The display 100 includes a display scene or real world set 110, and a background prop 112 and a foreground prop 114. The props 112, 114 are physical objects such as pieces of furniture that a “ghost” may walk among or, as shown for simplicity's sake, a box 112 and a ball 114. A sheet or piece of glass (e.g., a beam splitter) 118 is positioned at an angle (e.g., 45 degrees) between the scene 110 and the expected or planned position of the viewer 105 (or the viewer's point of view (POV)) or an outer display surface/window. The glass is at least partially transparent such that the background prop 112 and the foreground prop 114 are visible through the glass 118 as light 113, 115 travels through the glass 118 to the viewer or viewer's eyes 105. A display 120, such as a typical 2D monitor or a hidden room/scene that can be selectively lit, is provided in the display 100 and is used to display an image 124 such as the two-dimensional pyramid shown in FIG. 1A. The foreground prop 114 is in front of the “ghost” in image plane 126 but behind the beam splitter/glass pane 118.
Light 125 travels toward the beam splitter 118 where it is reflected 128 from the front (or viewer-side) of the beam splitter 118 toward the viewer 105. In this manner, a reflection 127 of the displayed image 124 is visible by the viewer 105 concurrently with light transmitted from the props 112, 114, and the reflection 127 may appear to be located (e.g., as a “ghost” or virtual image) between the background prop 112 and the foreground prop 114 through proper spacing of the display surface 122 relative to the front surface of the glass 118 and the locations of the props 112, 114. An additional foreground prop could be provided in front of the glass 118, and such a prop would occlude the “ghost” on plane 126 and background objects such as prop 112.
In the traditional Pepper's ghost display 100, a partially reflecting pane of glass or beam splitter 118 is used to overlay reflections 127 of a physical object or images 124 from a video or still monitor 120 on a real world scene 110. As shown in FIG. 1B, the reflected object 154 may be positioned between the background prop 152 and the foreground prop 156 from the perspective of the viewer 105, e.g., the virtual character/object plane 126 is between props 112, 114 in scene 110. Unfortunately, the virtual image (or reflection of the virtual or displayed object 124) 154 is semi-transparent (or translucent) and low contrast. This can be seen in FIG. 1B with the background object 152 being visible at 159 through the virtual image 154. Further, the image 154 appears flat or two-dimensional and is incapable of casting its own shadow as would be expected of a solid object in scene 110. The 3D effect is also spoiled in part when the reflection 127 is in front of the foreground image 156 as shown at 158. The translucence, lack of shadows, and flat appearance combine to spoil or hinder for a viewer 105 the illusion of a solid, virtual object integrated into the scene 110.
Hence, there remains a need for improved visual display techniques and systems such as for creating or projecting 3D images. Preferably, such an advanced Pepper's ghost display system would provide a higher contrast, solid or opaque-appearing, and 3D dimensional virtual character that can be interspersed or located among/between physical props such as physical foreground and background props. Further, in some cases, it may be useful for the advanced Pepper's ghost display system to be adapted such that displayed virtual objects (or images viewable by an observer) are capable of occluding physical objects (e.g., prevent portion 159 of background prop 152 from being viewed by viewer 105), of being occluded by physical objects in front of them or in front of the virtual character plane 126 (e.g., prevent potion 158 of virtual object 154 from being viewed on or in front of foreground prop 156), and of casting true dynamic shadows.